Chair back



FIG. 1 is a perspective view of chair back showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a reference view (a rear perspective view) thereof.

The broken line showing the remainder of the chair is for the purpose ofillustrating environmental structure and forms no part of the claimeddesign.

CLAIM The ornamental design for a “chair back,” as shown and described.